The objective of the Neurobiology Core is to provide state-of-the- art technical support for the neurobiological experimental projects on cerebral cortical development and to facilitate cross-project collaborations. The Core will provide shared technical expertise, equipment, facilities and staff to process experimental neural tissue in a regular and reliable fashion for the developmental neurobiology projects outlined in this proposal (and new projects that the investigators may initiate during the course of the Center's operation). In particular, the Neurobiology Core will provide a central cell and tissue processing facility for two of the four major projects to be undertaken in the Center and six of the sub-projects (those of Drs. Hablitz, Friedlander, Theibert, Garner and two of Dr. Sontheimer's). In each of these projects, experimental animal (rat) nervous system tissue (cortical neurons, oligodendrocyte precursors, astrocytes, cortical slices and intact cerebral cortex) from fetal and neonatal animals will be routinely processed in substantial volumes. For example, neuronal and glial cell cultures will be prepared weekly for most of the experiments. In addition, a series of sophisticated and time-consuming types of tissue processing will be carried out on a regular basis, including animal perfusions, histochemical processing for NADPH-diaphorase activity and horseradish peroxidase, immunocytochemical staining of cultural neurons and oligodendrocytes and thick and thin cortical sections, quantitative analysis (2- and 3-dimensional reconstructions of neural processes) from serial sections, correlated light-electron microscopy, immuno-electron microscopy including ultra-thin sectioning, en bloc and post-embedding immunostaining, photomicrography and serial reconstruction of synaptic profiles. It is the primary mission of the Neurobiology Core to provide high- level trained technical staff including one electron microscopist proficient in correlated L.M.-E.M. of immunostained neural tissue and quantitative morphometric analysis and one neurohistologist proficient in preparation and maintenance of neuronal/glial cell cultures and light microscopy level CNS tissue processing including immunocytochemistry, use of neural tracers and fluorescent probes, in situ hybridization and tissue autoradiography. While each investigator will work on their particular experiments with a postdoctoral fellow, the Core will provide for the standardized processing of cells and tissue, using techniques that are common to each of the six sub-projects. Thus, each investigator will not have to duplicate in their respective laboratory, the technicians and equipment for these functions. It is considerably more cost- efficient to l) have a single electron-microscopist who regularly works on cultured rat cortical neurons, oligodendrocytes and neonatal rat cortical tissue for a variety of experiments and 2) have a single neurohistologist also works with a wide range of techniques on neonatal cortical cells (including culture preparation, immunostaining of cultured neurons and cortical sections, in situ hybridization, calcium uptake studies in cortical sections and tissue autoradiography). Moreover, the Core Facility equipment including cell culture suite, electron microscope, image analysis facility and computers, cryostat, vibratomes and autoradiogram analyzer is not readily duplicated in each individual investigator's laboratory. Thus, the Core will provide this equipment which will be properly maintained, used by highly skilled technicians, optimally used in a number of projects and will lead to standardized quality control of tissue processing for several projects, and will be likely to result in methodological benefits to each individual investigator by sharing methods and experimental strategies through common personnel and facilities.